Tgf-\u03b21 transcriptionally promotes 90K expression: possible implications for cancer progression

Antonino Grassadonia,Sara Pagotto,Patrizia Vici,Nicola Tinari,Marco Marchisio,Cesidio Giuliani,Michele De Tursi,Vincenzo Graziano,Davide Brocco,Angelo Veronese,Maurizia D’Egidio,Pietro Di Marino,Paola Lanuti,Alessandro Cama,Laura De Lellis,Clara Natoli

doi:10.1038/s41420-021-00469-1

Abstract

The 90K protein, also known as Mac-2 BP or LGALS3BP, can activate the immune response in part by increasing major histocompatibility (MHC) class I levels. In studies on a non-immune cell model, the rat FRTL-5 cell line, we observed that transforming growth factor (TGF)-β1, like γ-interferon (IFN), increased 90K levels, despite its immunosuppressive functions and the ability to decrease MHC class I. To explain this paradoxical result, we investigated the mechanisms involved in the TGF-β1 regulation of 90K expression with the aim to demonstrate that TGF-β1 utilizes different molecular pathways to regulate the two genes. We found that TGF-β1 was able to increase the binding of Upstream Stimulatory Factors, USF1 and USF2, to an E-box element, CANNTG, at −1926 to −1921 bp, upstream of the interferon response element (IRE) in the 90K promoter. Thyrotropin (TSH) suppressed constitutive and γ-IFN-induced 90K expression by decreasing USF binding to the E-box. TGF-β1 was able to overcome TSH suppression at the transcriptional level by increasing USF binding to the E-box. We suggest that the ability of TGF-β1 to increase 90K did not result in an increase in MHC class I because of a separate suppressive action of TGF-β1 directly on the MHC class I gene. We propose that the increased levels of 90K may play a role, rather than in immune response, in the context of the TGF-β1-induced changing of the cellular microenvironment that predisposes to cell motility and cancer progression. Consistently, analyzing the publicly available cancer patient data sets cBioPortal, we found that 90K expression directly correlated with TGF-β1 and USFs and that high levels of 90K were significantly associated with increased mortality in patients affected by different types of cancer.

Highlights

Introduction TheTransforming growth factor-beta (TGF-β) polypeptides regulate the growth, function, and immune properties of cells[1]
Autoradiography of [35S]methionine-labeled proteins secreted by FRTL-5 cells and immunoprecipitated with a specific anti-90K antibody revealed the presence of a high molecular weight form of 90K (~200 kDa) and one of ~57 kDa, when cells were grown in 5H medium (Fig. 1C, lane 1)
Gene expression by increasing USF1 and USF2 binding to its promoter, in the same E-box involved in the hormonal regulation of the gene

Summary

Introduction

Transforming growth factor-beta (TGF-β) polypeptides regulate the growth, function, and immune properties of cells[1]. The prevalent role of TGF-β1 in the immune system is to induce tolerance and immune suppression[2], in part by inhibiting IL-2 production and NK activity[3,4], promoting the differentiation of naive T-cells into Treg via Foxp[3] transcription factor[5,6], and decreasing levels is clear since TGF-β1-deficient transgenic mice have increased MHC class I levels in many organs and develop a rapid, wasting, autoimmune disease[8]. Β1, 90K activates the immune defense systems of the organism[10]. Human 90K enhances the in vitro generation of cytotoxic effector cells (NK and LAK) from peripheral blood mononuclear cells (PBMC)[11]; increases IL-2 production by PBMC11 and increases MHC class I antigen expression in human breast cancer cells[12].

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